Scribing instrument, more particularly for lettering sets



E. WASSMANN Oct. 4, 1966 SCRIBING INSTRUMENT, MORE PARTICULARLY FOR LETTERING SETS Filed Oct. 20, 1964 In venlo 1.- 0 we Wa United States Patent 1 Claim. 61. ss 2s The invention relates, as indicated, to a scribing instrument, such as known in the art, and used preferably in conjunction with lettering sets or templates for scripting. Such scribing instruments comprise a scriber arm holding the writing instrument and the so-called tail pin and a tracer arm with a tracer pin, in which the tracer arm is connected detachably and adjust-ably with the scriber arm by means of a grub screw joint operable by a knob. To this end, the tracer arm has an oblong slotted guide receiving the grub screw joint so that, when this grub screw is tightened, the tracer arm is pressed firm-1y against the scriber arm.

With known scribing instruments of this kind, the scriber arm and the tracer arm consist each of a metal member, for example, stamped from a brass plate which must be machined and prepared in several successive operations before the instrument can be finally assembled. Moreover, the construction of these apparatus necessitates that the weight which is normally fitted near the tail pin must be arranged on the upper side of the scriber arm, thereby not only affecting the general appearance of the instrument, but also obstructing its proper and easy handling.

According to the persent invention, these drawbacks may be avoided in that at least the scriber arm is made by injection moulding from a high-grade synthetic resin, such as, for example, the material known as Makro'lon and is so formed that it has, at least over a part of its circumference, a downwardly bent edge or rim, forming a hollow cavity on its underside, in which the said weight may be mounted. Preferably the weight consists of a circular metal disc with a threaded bore in its centre, into which may be screwed from the top a screw carrying the tail .pin. According to a further feature of the invention, the said disc may have at one point of its circumference a groove into which engages a projection on the scriber arm so as to secure the disc against rotation.

By means of the arrangement hereinbefore described, both the drawbacks of hitherto known scribing instruments may be avoided and in addition, owing to the lower position of the weight, the stability of the instrument during its use is much improved.

The invention will be further described, by way of example, with reference to the accompanying drawing, in which:

FIG. 1 is a perspective view of a scribing instrument according to the invention;

FIG. 2 shows the instrument, viewed from below;

FIG. 3 is a partly sectionalized side elevation of the instrument;

FIG. 4 is a cross-section of the clamping screw joint;

FIG. 4a is a cross-section of the clamping screw;

FIG. 4b is a view of an associated intermediate washer.

The drawing shows the scriber arm 1, made of a synthetic resin and the tracer arm 2, equipped with an oblong guide slot, and connected to the former by a clamping screw. Preferably, also this tracer arm is made from synthetic resin.

3,276,125 Patented Oct. 4, 1966 ICC The tracer arm 2 carries a tail pin 3, as known in the art, and the scriber arm 1 carries a scribing tool, in this case a scribing pen 4, held in position by a clamping screw 5, 5". To this end, a knurled nut 5 is fitted on to a shaft screw, passing through a slot 4' and carrying at its other end a block-shaped projection 5" which engages into .a recess 5' of the scriber arm and secures the screw against rotation. The slot 4 communicates with the cylindrical opening of the scriber arm adapted to receive the pen 4. However, in contradiction to other, hitherto known clamping joints of this kind, the slot 4 does not extend to the outer end of the scriber arm.

A screw 6 serves as adjustable limit stop for the adjustment in height of the scriber pen 4, and is screwed into a tapped bore 6 provided in the scriber arm 1 during the injection moulding thereof.

A clamping knob 7 serves in conjunction with a screw 10 for clamping the tracer arm on the scriber arm in the desired position. The screw 10 carries at its lower end a hammer-shaped head 10", located in a correspondingly shaped recess 10' on the underside of the scriber arm and securing thereby the screw 10 against rotation. As may be seen from the cross-section in FIG. 4a, the shaft of the screw 10 is flattened on both sides; between the clamping knob 7 and the surface of the tracer arm 2, there is an intermediate washer 11, the centre opening of which is adapted to the flattened cross-section of the shaft of the screw 10, so that the washer 11 is also secured against rotation when the knob 7 is tightened.

As may be seen from FIGS. 2 and 3, the scriber arm 1 has over a portion of its circumference a downwardly bent edge 1', forming a hollow cavity at its underside, adapted to receive a weight 9. The weight 9 consists of a circular disc with a threaded centre bore into which engages from the top the screw 8 carrying at its lower end the tail pin. At one .point of its circumference, the weight disc 9 is equipped with a groove 9" into which engages a lug 9' provided on the edge 1' so that the disc 9 is secured against rotation when the screw 8 is tightened.

Having thus fully disclosed and described the invention, what I claim and desire to secure by Letters Patent is:

A scribing instrument comprising:

a tracer arm having an elongated slot provided there in, said tracer arm having a tracer pin secured to one end thereof;

a scribing arm having a scribing tool secured at one end thereof and a tail pin receiving aperture at its opposite end thereof, said scribing arm further including a clamp joint receiving aperture intermediate its ends thereof and being further provided with a downwardly bent edge along part of its periphery to form a weigh-t receiving cavity on the underside of said scribing arm, said cavity communicating with said tail pin receiving aperture, said downwardly bent edge including a lug which extends into said cavity;

a clamp joint detachably passing through said elongated slot of said tracer arm and said clamp joint receiving aperture of said scribing arm to detachably and adjustably join said tracer arm and said scribing arm together;

a circular metal disc located in said cavity in the underside of said scribing arm, said disc having a threaded center bore which communicates with said tail pin receiving aperture and a groove at one point along its periphery which receives said lug to prevent relative rotation therebetween; and

3 41 a screw threaded tail pin passing through said tail pin References Cited by the Examiner receiving aperture of said scribing arm into screw- UNITED STATES PATENTS threaded engagement with said threaded center bore of said disc, said tail pin including a head at one 9051357 12/1908 Perks 33107 X end thereof and a pointed portion at its other end 5 25741664 11/1951 Schnelder 33-23 thereof, said pointed portion of said tail pin project- 2,309,431 10/1957 33-23 in-g out of said bore for engagement with the surface upon which said scribing instrument is to be FOREIGN PATENTS used; 803,586 4/1951 Germany.

whereby the securement of said disc within said cavity 10 950,093 10/ 1956 Germany.

increases the aesthetic appearance of said scribing instrument, distributes the Weight of said disc at a LEONARD FORMAN, Prlmary Examine!- lower point relative to said surface, and results in a ROBERT B. HULL, Emmi-net relatlvely smooth upper surface on said opposlte end of said scribing arm. 15 H. N. HAROIAN, Assistant Examiner. 

